Wednesday, July 21, 2010

A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity....MORE, including track and intensity forecasts.

From the Houston Chronicle's SciGuy:

Tropical wave weakens a bit, but it's aiming toward Gulf spill

After showing signs of organizing late Tuesday, wind shear inhibited a disturbance dubbed 97L from strengthening into a tropical storm this morning. As a result chances that the tropical wave, moving north of Puerto Rico and Hispaniola, will form a tropical depression today or tomorrow have fallen to 60 percent....

...The track models are actually in quite good agreement for 97L, a surprise given its lack of a well-defined circulation. They show the system crossing southern Florida on Friday and then emerging into the eastern Gulf of Mexico:

Colo. State

If and when it gets back into the Gulf of Mexico, present computer tracks of the storm bring it right over the oil spill (see map), which is why this system bears close watching. By late Sunday or Monday it should come ashore between the Mississippi River and the Florida panhandle....MORE